Investigations about the influence of some physiological and phenological characteristics on quality and their heredity

Abstract

The analysis of the offspring of 6 crossings with a total of 360 genotypes revealed that, of a total of 13 characteristics taken into account by the investigations, only the yield or the yield components, the beginning of berry ripening and the degree of botrytis infection have a significant influence on the sugar content of the must. About 60% of the fluctuations in the sugar content of the must could be explained by these, whereby at approx. 35% the beginning of berry ripening accounted for the highest percentage. The coefficient of determination for the three yield parameters which were investigated was between 12 and 19%. The weight of the berries was the most important factor, while the number of clusters per shoot was nearly neutral with respect to its effect on the sugar content of the must. Consideration of these relations when selecting seedlings may, if only to a limited extent, lead to an increase in the success of selection for varieties with a high sugar content. It should be mentioned that these results, which were reached under the climatic conditions of Central Europe, cannot necessarily be applied to wine growing areas in other climates.
Some of the heritability levels determined differ considerably for the individual characteristics. While a low heritability coefficient was ascertained for the number of clusters per shoot, the single berry weight and the beginning of berry ripening indicate a high percentage of additive genetic effect, i.e. their degree in the offspring can be influenced to a great extent by the selection of the parents for crossing combinations.
By taking into account both the heritability levels when making the crossing combinations and the relations between these characteristics and the sugar content of the berries when selecting, a breeding programme to increase the sugar content is likely to make rapid progress. In addition, the selection criteria pointed out may be useful in clonal selection with regard to better quality. Last but not least, values for combining ability, which can be calculated by a similar model of variance analysis, may help by the identification of varieties.